Just for my own curiosity, I was taking a free MOOC at coursera.org about complex analysis, you know like about the Mandelbrot set and Cauchy-Riemann equations. But not being super smart, I needed help! I found a grad student nearby who charged $50/hour so I hired him for some help. But then I found KJS Tutoring which had an active Groupon going on. I joined Groupon, got their promotional discount for first-time Groupon users, then bought the KJS Tutoring Groupon, and voila! I have a two hours of very affordable (almost free) tutoring in a difficult math subject via Skype from KJS Tutoring!
Love that Groupon.